Electric perforating tool



Fab. 17, 1931. J. M. GRAFF 1,792,683

ELECTRIC PERFORATING TCOL Filed Oct. 28, 1929- 9 WAT i v W 2.

r t M Patented Feb. 17, 1931 UNITED STATES JAMES m. GRAFF, 0F BALTImoRaMARYLANn ELECTRIC PERFORATING TOOL Application filed October 28, 1929. Serial No. 402,911.

This invention relates to perforating tools and has special reference to a tool for burning holes through fabric packing placed between plates of metal originally punched "with matched holes.

More particularly the invention relates to a tool of this character wherein the piercing or perforating element forms part of a high tension electric circuit.

One object of the invention is to provide an improved general construction of tool for this purpose.

A second important object of the invention is to provide a tool of this character wherein the tool will he provided with a transformer so that ordinary house or shop current may be used to operate the tool, the piercing or perforating element being connected to short circuit the transformer secondary.

A third important object of the invention is to provide an improved tool of this character wherein the piercing element is of rugged formation so that it will stand up under hard and continuous service.

With the above and other objects in view, as will be presently apparent, the invention consists in general of certain novel details of construction and combinations of parts here inafter fully described, illustrated in the accompanying drawings and specifically claimed.

In the accompanying drawings like characters of reference indicate like parts in the several views, and

Figure 1 is a side elevation of the invention. I

Figure 2 is an end view thereof.

Figure 3 is a detail section on line 3-3 of Figure 2.

In the embodiment of the invention herein illustrated it will be seen that the tool is provided with a handle 10 of ordinary shape and the forward end of this handle carries an ordinary transformer 11 wherein the primary winding is designed to carry the current used in the shop or other location in which it is. intended to use the tool. The secondary winding of the transformer is provided with a pair of terminal prongs 12 and is so designed'as to properly heat the piercing point of the tool. This point consists of a rectangular block 14 of highly conductive material such as copper or the like, and this block is provided with a conical nose 15. The base of this block is provided with suitable sockets to receive the prongs 12 and set-screws 16 extend through opposite side portions of the block to engage said prongs and hold the point in position. This point is slit as at 16 from the base to and nearly through the nose, a small bridge 17 being left at the tip of the nose to connect the two halves of the point, these being otherwise separated. Thus the transformer secondary is short circuited through this bridge 17 and heats it to such an extent that it will readily pierce a hole through fabric to which it is applied. It will be noted that, while the bridge is so small that it heats up very readily, it is strongly supported by the heavy nose and base of the tool point. This point is surrounded at its base by an insulating collar 18 so as to prevent the current shorting through a path other than the bridge. Flexible con- 7 ductors 19 serve to connect the tool to a suitable source of current and pass through the handle to the transformer primary.

There has thus been provided a simple and efficient device of the kind described and for the purpose specified.

It is obvious that many minor changes may be made in the form and construction of the invention without departing from the material principles thereof. It is not therefore desired to confine the invention to the exact form herein shown and described, but it is wished to include all such as properly come within the scope claimed.

Having thus described the invention, What is claimed as new, is v In a tool of the class described, a handle, a transformer carried by the handle and having primary and secondary windings sai'd secondary Winding terminating in a pair of spaced terminal prongs, and a conductive pierceing point consisting of a base socketed to receive said terminal prongs and seated thereon, a conical nose anda narrow bridge at the tip of the nose, said point having a slit extending through the base and point to the bridge, saidslit being positionedbetween the sockets of the base.

In testimony whereof- I affix my signature.

JAMES 'M. GRAFF. 

